The interpretation is based on the appearance of this word in other rabbinic Hebrew texts related to this passage. See Jastrow and DJBA s.v. רצינתא. The scribe here apparently thought it was a verbal form, however, hence ולא instead of דלא. The etymology, though, (for which compare Levy and Jastrow), remains uncertain. The standard edition of the Talmud (BB 91b) reads: ת"ר ואכלתם מן התבואה ישן בלא סלמנטון מאי בלא סלמנטון רב נחמן אמר בלא רצינתא ורב ששת אמר בלא שדיפא : the sages taught: you shall eat from the old grain (Lev. 25:22) means without s’. What is "without s’?" PN1 said without רצינתא while PN2 said without blast. Page refs. in other dictionaries: Jastrow: 995; Levy Ch-W: 2:167;